A recurring nightmare for parents is to be separated from their child in a crowded environment such as a shopping mall. The child could wander off and get lost. This could provide an opportunity for kidnapping or injury. There is a need for a device which alerts the guardian, the child, and persons in the vicinity of the child of a potential problem if the child is not in the proximity of the guardian. Previous efforts to solve this and related problems are covered in the following patents.
U.S. Pat. No. 4,136,338 (1979) to Antenore discloses an area perimeter alarm system using a buried wire. A monitored user carries a transmitter which imposes a signal on the wire. When the user strays beyond the perimeter, an alarm is triggered.
U.S. Pat. No. 4,476,469 (1984) to Lander discloses a locator means for assisting in locating an object. It comprises a hand held searcher and a miniature locator which can be manually activated to find a key ring and the like.
U.S. Pat. No. 4,593,273 (1986) to Narcisse discloses an out-of-range personnel monitor and alarm suited for mental institutions. The system has a base unit that transmits to a mobile unit. If the mobile unit loses signal strength, it transmits that information to the base unit triggering an alarm.
U.S. Pat. No. 4,694,284 (1987) to Leveille et al. discloses a radio transmitter in a band worn by a child. Even if the band is unlocked the radio signal continues, thereby enabling a rescue attempt.
U.S. Pat. No. 4,785,291 (1988) to Hawthorne discloses a child alarm system. The receiver AGC level provides an LED and audible alarm upon preset distance being attained from the child.
U.S. Pat. No. 4,888,580 (1989) to Distel discloses a string activated magnetic alarm switch.
U.S. Pat. No. 4,973,944 (1990) to Maletta discloses RF circuitry mounted on a user. When the user leaves an area boundary set by a receiver, the receiver alarms. Also taught is a mounting band for the RF circuitry which, if broken, also sounds an alarm.
U.S. Pat. No. 4,899,135 (1990) to Ghahariiran discloses an ultra sonic based child alarm system. If the child strays, then the guardian's unit alarms. The guardian can then activate an audio alarm in the child's transceiver to assist locating the child.
U.S. Pat. No. 4,999,613 (1991) to Williamson et al. discloses a prisoner monitoring system.
U.S. Pat. No. 5,021,794 (1991) to Lawrence discloses a UHF radio direction finding system for a lost child.
U.S. Pat. No. 5,119,072 (1992) to Hemingway discloses a child alarm system using FM RF signals to send a first distance calculating signal to determine proximity. Then a second microphone signal is transmitted when the child strays from the mother.
U.S. Pat. No. 5,115,223 (1992) to Moody discloses a monitoring and tracking system. The user's band is tamper resistant. Radio signals indicate distance and direction of the user.
U.S. Pat. No. 5,175,868 (1992) to Yasuoka discloses a radio interference resistant lost child transmitter/receiver.
U.S. Pat. No. 5,196,825 (1993) to Young discloses a child's homing device also having a child activated alarm sending transmitter.
U.S. Pat. No. 5,235,322 (1993) to Obysovsky et al. discloses a manually activated wrist band audio alarm system to prevent mugging.
U.S. Pat. No. 5,245,314 (1993) to Kah, Jr. discloses an RF signal location monitor. An intermittent battery saving transmitter activates an alarm sounding receiver.
U.S. Pat. No. 5,289,163 (1994) to Perez et al. discloses a child alarm system using RF signals. A direction indicator using LEDs helps the guardian walk toward the location of the child who has strayed beyond a preset distance.
U.S. Pat. No. 5,298,883 (1994) to Pilney et al. discloses a pair of transmitter/receivers which audibly beep at a rate relative to separation distance. A direction finder is included.
U.S. Pat. No. 5,307,763 (1994) to Arthur et al. discloses a buried wire area alarm system.
Applicant believes that '135 is the closest known prior art. The present invention is similar to '135 in that the child can be alarmed, but with '135 the alarm trigger requires a second transmitter link and human intervention. With the present invention the child is virtually an electronic time bomb waiting for the triggering event to occur. Thus, the present invention is simpler in functionality than the prior art and eliminates human intervention. The child's alarm will be activated when the child leaves the preset perimeter of the guardian. The alarm will also be activated when the child's harness is tampered with by a perpetrator. Additionally, the child can set off his own alarm purposefully if he is molested. The present invention differs from the prior art by: 1) The child's alarm device is intended to automatically alert everyone around the child that he is possibly in serious trouble. All the people can then be witnesses, or can possibly assist in rescuing or helping the child. 2) The guardian can alternatively control a one-way transmission because he has the only transmitter, and he can activate the child's receiver at any time to locate him.
In summary, the present invention is the only known invention which focuses on automatically setting off an alarm on the child when he wanders beyond a preset distance from his guardian.